Artificial island and method of constructing the same



D 4, 1953 J. H. THORNLEY ARTIFICIAL ISLAND AND METHOD OF CONSTRUCTINGTHE SAME Original Filed Sept. 5, 1956 3 Sheets-Sheet 1- INVENTOR- jiiuafi BM gave/A BM Dec. 24, 1963 J. H. THORNLEY 3,115,013

ARTIFICIAL ISLAND AND METHOD OF CONSTRUCTING THE SAME Original FiledSept. 5, 1956 1 3 Sheets-Sheet 2 ARTIFICIAL ISLAND AND METHOD OF.CONSTRUCTING THE SAME Original Filed Sept. 5, 1956 Dec. 24, 1963 J. H.THORNLEY 3 Sheets-Sheet 3 United States Patent 3,115,013 ARTEFECHALISLAND AND METHQD @F CQNSTRUCTHNG THE SAME Eoseph H. Thornley, 25% WestDrive,

Douglaston, N.Y. N

@riginai application Sept. 5, 1956, Ser. No. 668,019.

Divided and this appiieaion May 2, 1953, er. No.

Claims. (Cl. til-46.5)

The present invention relates to artificial islands, and to improvedmethods of and improved apparatus for erecting such islands. Theapplication is a division of my copending application Serial No.608,079, filed September 5, 1956, and now abandoned.

Recent developments in our national defense and 1n the oil industry havegiven rise to demand for artificial islands along the coastal areas ofthe country for radar installations and off-shore drilling rigs. in bothcases, the islands may be only temporary and, therefore, must beeconomical, relatively easy to erect, and capable of being easilydismantled so as to cause no permanent obstruction to navigation. Yet,in use, the islands must be completely stable and therefore require afixed foundation. When installed, such islands are subject to littlevertical load, but live horizontal loading is large and of variabledirection and magnitude as caused by shifting winds, currents, tides andwaves. The demands thus imposed upon the structure obviously do notadmit of a conventional solid masonry foundation, nor is theconventional pile form of support adequate. Specifically, horizontalload is delivered to a pile by cantilever beam reaction set up when theforce tends to cause lateral movement at the upper end of the pile.Therefore, the optimum load sustaining characteristic of the pile, i.e.,in compression, is not utilized in cases of dominant horizontal load.Moreover, the pile foundation suffers the disadvantage of requiring firmoverburden at a limited depth, a situation not always encountered inoff-shore areas, since resistance of the pile to horizontal loading isin inverse proportion to depth, i.e., stability is lost in directproportion to increase in depth. Thus, masonry and pile foundations arenot the answer to the problem.

It is one object of the present invention to provide an improvedartificial island meeting and fully satisfying all of the demands of theart, and in particular, to provide an island that is economical, easy toerect, completely stable under the most severe conditions of horizontalloading without any required vertical load, and capable of being readilyand completely dismantled.

' Another object of the invention is the provision of an improvedartificial island comprising at least three bottom anchored top joinedconical skeletal foundation units disposed preferably in spacedgeometric relation as viewed in plan, each unit comprising at leastthree downwardly divergent rigid elongate supports connected together attheir upper ends and firmly anchored at their lower ends to sustain loadin compression or tension longitudinally thereof, the supports of eachunit extending above peak water level, and a barge slidably mounted onthe upper end portions of the supports of each unit.

It is also an object of the present invention to provide an improvedmethod of and improved apparatus for erecting artificial islands,especially my said improved island.

An additional object is to provide an improved method of and apparatusfor erecting foundations in water courses, at sea, and in tidal areas,either as a temporary or permanent foundation.

Yet another object of the invention is to provide an improved method ofand apparatus for erecting my said island, wherein a single barge isemployed, first, to caryy the materials of construction to the site,second, to serve ice as the erection plateform, third, to guide thecaissons during erection, fourth, to constitute the means connecting theupper ends of the foundation units, and fifth, to comprise the islandper se in the complete construction.

A further object of the invention is the provision of improved apparatusfor erecting and comprising an offshore island, including a buoyantbarge having at spaced points thereon at least three groups of guidemeans, each group including at least three guide means disposed on abatter the axes of which define a downwardly divergent conical skeleton,a plurality of rigid elongate supports, crane means on said barge forlifting and placing one of said supports in each of said guide means andfor driving each support at a batter under the guidance of the respective means downwardly relative to said barge to rigid anchorage todefine a stable conical skeletal foundation unit at each of said points,and hoist means on said barge for lifting the same upwardly on the upperextensions of said supports to dispose the barge above peak water level,whereby said barge comprises the vessel for carrying the apparatus tothe island site, the plateform for erecting said foundation units andthe island per so.

A still further object of the invention is the provision of an improvedmethod of foundation erection as above defined including the steps offloating the barge to the site, util zing the same as a work platform todrive the caissons, with portions of the caissons projecting above theplatform, and subsequently elevating the barge on the caissons todispose the same above peak water level to avoid as far as practicablethe adverse effects of tidal and wave action.

Other objects and advantages of the invention will become apparent inthe following detailed description.

Now, in order to acquaint those skilled in the art With my improvedartificial island and my method of and apparatus for erecting the same,I shall describe, in connection with the accompanying drawings, apreferred embodiment of my island, the preferred apparatus used inerection of the island, and the preferred method of erecting and usingthe island.

In the drawings, wherein like reference numerals indi cate like parts:

FIGURE 1 is a side view of my improved artificial island, the viewshowing the caissons of the tripod unit to the left of the Viewpermanently set and the caissons of the tripod unit to the right of theview temporarily set, the barge, platform, or island being shown indotted lines in its initial position and in solid lines in its finalpostion;

FIGURE 2 is a top view of the island of FIGURE 1, the view being takensubstantially on line 2-2 of FIG- URE 1;

FIGURE 3 is a somewhat schematic fragmentary representation of the bargeand equipment employed in erection of the island; and

FIGURE 4 is a fragmentary vertical section of a caisson and anchoringmeans therefor showing, first, an improved manner of anchoring a caissonother than by imbedding the same in bed rock, and second, an improveddevice for attaching the caisson to its anchor, whether that be bed rockor other means.

Referring now to FIGURES 1 and 2, I have shown an improved foundationfor use as an artificial island that is stable under all loadingconditions and is particularly adapted to support live horizontal loadsapplied in any direction. The foundation construction is comprised of aplurality of the anchored tripod or conical units it! of my saidco-pending parent application, preferably at least three in number, anddisposed in spaced triangular or o" ier geometric relation, as indicatedrespectively at Ma, iii!) and Zlfic, and a member 42 supported on theupper end portions of the tripod units. Each conical tripod unit it?comprises at least three mutually downwardly divergent supports orcaissons 2t), 22 and 24. The carssons are immovably anchored at theirlower ends and extend upwardly above the surface of the water. The axesof the caissons of each unit have a common point of intersectionsubstantially above the surface, the caissons terminating somewhat belowthat point but above surface level, i.e., above the surface of the waterin which the structure is erected, and being rigidly but detaehably connected at their upper ends by a cap 26a, 26b, and 260, respectively. Thecap members, or the points of intersection defined by the several tripodor conical units, are disposed in geometric relation, a triangle in thecase of three units as is shown in FIGURE 2, whereby spaced stablepoints or areas of support are provided.

Each unit individually is a highly stable instrumentality, the legs orcaissons thereof being especially adapted for loading in bothcompression and tension. However, each unit individually suffers the onedisadvantage that the caissons or supports thereof have a common axis ofrotation and therefore cannot be stressed in the direction of thelongitudinal axis upon application of a torque couple in the horizontalplane. For resolution of straight line forces, optimum design dictates acommon point of caisson intersection, but the stated disadvantage thenresults. When three or more units have their apexes disposed insubstantially a common horizontal plane and said apexes are rigidlyinterconnected as by a frame or platform, then they are capable ofsustaining horizontal or vertical or twisting loads upon said frame orplatform. Resistance to all overturning forces applied to the apex of aunit will be developed as tension or compression longitudinally of theindividual caissons. The caissons are of ample strength to sustain theload in shear which results from horizontally acting forces or forcecomponents.

The preferred embodiment of the foundation unit of my invention is thesymmetrical arrangement of the caissons on an equal predetermined batterhaving their lower ends connected to firm earth strata with an anchoragewhich is able to develop the full strength of the caisson in eithertension or compression, and having the upper ends of the caissonsconverging to substantially a common intersection or apex and havingsaid upper ends joined together in a cap with a connection to each otherwhich is able to develop the full strength of the eaissons in eithertension or compression. This structure has remarkable properties, someof which are as follows:

(1) The unit develops resistance to horizontal forces applied at the capand tending to overturn the unit, by developing tension and compressionin the eaissons. The strength of the structure to resist such load inany compass direction is substantially uniform. No vertical load isrequired to develop this property.

(2) The height to which the cap is carried above the base anchorage doesnot (within wide limits, and theoretically with no limits) affect thestrength of the structure, for a given cross sectional size of caisson,to resist such overturning forces.

(3) The height of the unit or the direction of the horizontal force hasno effect upon shear stresses which are the same for all heights and forall compass directions of the design load.

(4) For a given cross sectional size of caisson, the vertical loadbearing value and stability of the unit is independent of the height ofthe structure.

(5) For developing resistance to a horizontal force at any reasonabledistance above firm earth strata and from any compass direction, such,for example, as providing support for an off-shore drilling platform forany reasonable depth of water, the aforesaid unit requires a minimum ofmaterial and installation cost. No other known structure of equalstrength and stability approaches it in economy and case ofconstruction.

(6) For a given foundation value, after being put into service, itrequires a minimum of difficulty for its removal.

The member 4-2, being mounted on and connecting the upper end portionsof the supports or caissons of all of the tripod units, thus issupported by the units against all forces that could be applied to thefoundation. Moreover, the several units support the member 42 over anexceedingly large area of bed rock or rigid anchorage. Due to thedownwardly divergent batter to the caissons in each unit and the fixedanchorage thereof, the area of anchorage encompassed by the nine or morecaissons is large and is incorporated directly in the foundationconstruction as an integral part thereof. The caissons effectively raisethat area of anchorage to the surface, so that the member 42, which isof relatively small area, is effectively bonded in and supported by amuch larger volume of rigid anchorage. The member 42 thus is completelystable under all loading conditions irrespective of the forces and thedirection of the resultant of the forces applied thereto. In particular,the foundation is especially adapted to installations wherein verticalloading is slight and horizontal forces are large, and of variablemagnitude and direction.

By way of example, considerable interest has arisen recently inoff-shore oil fields in the Gulf of Mexico and in the Pacific Ocean offthe California coast. For operating at producing well in these fields, afixed, semi-permanent artificial island is required. The island shouldbe disposed above peak water level and must resist all forces appliedthereto and support the oil pumping and storing equipment. For suchislands, the loading problem is severe, residing primarily in thehorizontally applied forces consequent upon wind and wave action. Theprincipal load thus is a lateral force exerted at any point 360 degreesaround the island, and its intensity may vary from Zero during a deadcalm to the extreme upper limits imposed by a hurricane. Foundationdesigns previously known to the art are not well suited for resistanceto such loading. However, my improved foundation structure as shown inFIGURES l and 2 is ideally suited for this specific purpose, beingstable under all load conditions. Thus, the invention affords an optimumsolution to a specific current problem.

However, this problem is not the only one presently encountered in theoff-shore oil fields, and it is an object of the invention to afford acomplete solution of the problems concerning the instrumentalities fromwhich drilling and production must be carried out. Specifically, toreach the oil in the off-shore fields, exploratory wells must first bedrilled. To carry out the drilling operations, a drilling platform inthe nature of a fixed island is required. If the drilling brings in aproducing well, a permanent island is necessary, but if a producing wellis not brought in, all of the equipment must be removed, at least at themud line, so as to leave no obstruction to navigation.

With the equipment presently known to the art, feasible drillingplatform designs are frequently limited to use in water depths up toabout 50 feet, and up to 100 feet as a maximum, and then only in areaswhere the soil overburden is suitable to carry concentrated loads at areasonable depth. Many of the rigs available to the art are usable onlyduring periods of relatively calm whether and are not capable of use asdrilling platforms in violent sea, or during the hurricane season in theGulf of Mexico or the stormy season in the Pacific. Moreover, in thePacific, depths frequently will be in excess of that feasible for knowndesigns, and the soil overburden is too shallow and the rock profile tooirregular reasonably to permit of use of conventional apparatus.Currents and wave action also tend to undermine known apparatus andseriously mitigate against maintaining the drilling platform stationary.If drilling brings in a producing well, then the permanent island forwell operation must be erected separately of the drilling platform.

To overcome the disadvantages of known apparatus and methods, and toincrease appreciably the areas of exploration and operation in offshoreoil fields, the present invention provides improved foundation means,and an improved method of and apparatus for constructing and using thesame, that are suited for orT-shore oil exploration and production.According to the invention, the practical depths of operation areincreased to upward of 300 feet, soil overburden or lack thereof is nota factor controlling use of the equipment, cost is decreased, stabil ityis increased, and the drilling platform is retained stationary despitethe action of the sea. If a well is not brought in, the equipment isreadily moved for use at another site, and if a producing well isbrought in, part of the equipment used for the exploratory drillingbecomes the permanent island foundation structure of FIG- URES 1 and 2,and the remainder of the equipment may be removed for use elsewhere.

In bringing tire foregoing advantages to practical fruition, the basicequipment employed by me, in its simplest form, is the foundationstructure of FIGURES l and 2 embodied in the manner schematically shownin FIG- URE 3. As shown in FIGURES l to 3, the member 42 comprises abuoyant barge generally of triangular configuration having at each ofthe three corners thereof three batter slots 44 disposed in starrelation. Also at each corner, I provide a tower 46 extending upwardlyfrom the barge deck and carrying guide collar means 48 at the upper endthereof. Each tower structure also includes locking means 59 adjacentthe barge deck for a purpose to be described. Preferably, three guidecollars and three locking rings are provided at each corner alignedrespectively with the outer batter surface of the three slots as shownin FIGURE 3.

As to size, I contemplate that maximum loading conditions and spacerequirements should result in a design wherein, for purposes of exampleonly, the barge may be approximately 160 feet long, 80 feet wide and 18feet deep, having a draft under maximum load of feet. The shells of thecaissons may be from about 2 /2 to about 4 feet or more in diameter, asoccasion requires, and wall thickness may be of the order of 1 to 1 /2inches more or less, depending upon circumstances and the composition ofthe pipe, the slots 44-, guides .13 and rings 5t) being of a size toaccommodate and guide the shells. Major deck equipment, in addition tothe guides 4-5 and rings St includes means for anchoring the bargeduring erection of the foundation units, means for placing the caissonsin the guides, for driving the caissons to rigid anchorage and forsubsequently raising the barge on the caissons, and the necessaryauxiliary gear. The lifting means may, for example, comprise a fifty-toncapacity crane 52 with controlled travel of eighty feet along the majoraxis of the barge, or two fifty-ton capacity stiff leg derriclcs, orsuitable jacks. The caisson driving means suitably comprises a 24,000ft.-lb. impact, differential or single acting steam hammer with thenecessary boiler, leads, etc. If jacks are not provided between thebarge and the caissons, l contemplate the use of three sets of blocksand tackle 54 for raising the barge on the caissons, each set to developapproximately 1260 tons and be operated by single or double hoists 56developing a whipline pull of approximately sixty tons. The anchoringmeans preferably comprises three or more 2600 or 3000 lb. Danforthanchors with cable to give sufiicient rode to hold the barge inapproximate position in the maximum wind anticipated during erection.

Prior to the start of the drilling operation, a careful sounding andcore boring operation will be carried out to determine rock contours andthe nature of overburden and of bed rock.

To commence operations, the barge 42 is floated on the body of water inwhich exploratory drilling is (to be carried out and the equipment,including the caisson components, is loaded on the barge. The barge isthen towed to the drilling site. Upon nearing the well location, ninecaisson pipes 28, each perhaps 160 feet long, will have been threaded bymeans of the crane 52 through the guide collars 48, locking rings 50 andbatter slots 44, the pipes in their initial position, dependent upon thedepth of the water, extending 30 or feet below the bottom of the bargeas shown in FlGURE 3 and being guided by the collars 43 above the deck.The degree of batter, about 1:8, is calculated for the maximum initialthrust of wind and wave action and for the maximum final lateral loadunder the worst possible conditions, the batter, anchorage and thicknessbeing adjusted accordingly. Each pipe passes through a locking ring atdeck level so (that it may be restrained from descending under its ownweight. When the time comes to lower a pipe, it will be raised slightlyby the derrick or crane to free the locking ring wedges and then loweredto the required position. At its lower end, each of the nine pipes orshells 28 carries a tool steel tempered cutting or drive ring 30 and atits upper end an internal or external splice ring 38.

When the barge reaches the drilling site, three or more anchors areplaced to retain the barge in position. Assuming water depth at thedrill site to be 200 feet at mean high tide, and the overburden tocomprise 15 feet of silt and sand overlying medium hard bed rock havingan irregular surface, the foundation is set as follows: The firstsection of the shell of each caisson is lowered by the crane 52, afterrelease of the lock 50 in the manner described, to the top of the decktower. The second sections of the caissons, which may each be feet ormore or less long, are then set over the splice sleeves 38 at the top ofthe first sections and a team of two or three welders to each threecaisson group welds the second sections to the lower sections. Thelocking rings are again released and all pipes lowered until theycontact the rock. Each of the nine caisson pipes is then driven torefusal on or in the rock, using the heavy duty hammer. Thereafter, aremovable head cap (26a, 26b or 260) is mounted and clamped on each ofthe tripod caisson groups or conical foundation units.

In the above situation, wherein bed rock is not particularly deep andsoil overburden is shallow, the caisson shells are driven to bed rock asdescribed. However, if bed rock were considerably deeper, and firm soiloverburden were of substantial depth, concrete pedestals could be drivenout in the overburden as illustrated in FIGURE 4. Specifically, asshown, a substitute for bed rock may be employed in instances whereinthe substitute can be provided at greater economy and with greaterpracticality than driving the caissons to bed rock. In certain areas, itwill be found [that the strata of the earth are such that bed rock isexceedingly deep and there is a great depth of firm soil overlying bedrock. Under these conditions, it is practical, both commercially andfrom the standpoint of structural rigidity, to substitute for bed rockhuge pedestals formed by the driving out of large bodies of concreteinto the overburden, the depth in the overburden at which the pedestalsare formed, together with the volume of concrete used, governing theload capacity of the fabricated anchor either in tension or compression.In such case, the caissons would be driven to a firm seat on thepedestals, preferably to refusal after the concrete had set so that thecaissons could readily be removed for the purpose and under thecircumstances to be described hereinafter.

After the caisson shells have been driven to refusal, spiders or swaybracings 58 are installed on each conical unit, the spiders beingmounted on land rigidifying the caissons of each unit intermediate bedrock and the platform 42. Each spider may suitably comprise threecollars 6t slidably mounted respectively on the caisson shells, andthree horizontal ties 62, for example 12 inch diameter pipes, extendingbetween and detach-ably connected to the collars. Due to the downwardlydivergent relationship of the caissons, the spider by its own weightwill slide down into locking engagement on the pipes.

Dependent upon expected weather and/or sea conditions during exploratorydrilling, the caisson shells of each of the conical units may be bondedto their anchors, i.e., bed rock or a suitable pedestal, in any one ofseveral manners. For temporarily bonding each caisson to its anchor, thesimplest procedure is to deposit concrete within the lower end of eachcaisson shell to extend a short distance into the shell, as indicated bythe concrete plug 64 in the caissons of the unit 1015 at the right sideof FIGURE 1. For purposes of rigid bonding, a socket 66 is drilled priorto setting the concrete plug 64, and a short axial re-enforcing stub 68of a length to extend upwardly from the socket a short distance into thepipe is employed, as shown at the left side of FIGURE 1. Alternatively,for either permanent or temporary anchorage, an anchoring device of thecharacter disclosed in FIGURE 4 may be employed.

In FIGURE 4, the anchoring device, indicated at 76, is shown as beingbonded in a concrete pedestal. It is to be appreciated, however, thatthe anchoring device may be applied with equal facility in bed rock. Asshown, the device comprises one or more annular bearing plates 72supported in the interior of the caisson shell adjacent the lower endthereof by brackets 74 welded to the wall of the shell. The centralopening in the bearing plates may, for example, be about 20 inches indiameter to accommodate passage therethrough of a drill after the shellhas been driven to refusal on bed rock or a pedestal. The drill isoperated in the manner previously described to produce a socket 76 belowthe cutting shoe of the shell, which socket may, by way of example,extend approximately 6 feet below the shoe. When the socket iscompleted, the drill is removed and grout, indicated at 78, is placed inthe socket to a depth of five feet or so in the example given. Beforethe grout sets, an anchor member 80 is set axially in the socket 76 andimbedded in the grout therein, the member suitably comprising a piece ofshafting of the necessary diameter to take the calculated uplift and aheavy base plate of approximately the maximum diameter that can beaccommodated in the socket. At its upper end, the shaft of the member 89is threaded for the reception of a sleeve coupling 82. The member 80 andcoupling 82 are preferably assembled and lowered as a unit into thegrout, and are located in the socket with the upper portions of thecoupling protruding above the surface of the grout. When the grout isset, the members 80 and 82 are rigidly bonded in bed rock or in apedestal elfectively to constitute a unitary part thereof and to providea handle on bed rock or the pedestal for attachment thereto of thecaisson shell. In the embodiment disclosed, attachment of the caissonshell is effected by means of a second or top anchoring member 84comprising a piece of shafting of the same diameter as the bottom member80 and a bearing flange 36 of a diameter greater than the inner diameterof the bearing plates 72, the flange 86 being welded to the shaftadjacent, but in spaced relation to, the upper end thereof. The shaft ofthe top member 84 is threaded at its lower end for attachment to thecoupling sleeve 82 and is squared at its upper end to accommodate awrench by means of which the top member may be threaded into the sleeveto force the flange 86 into secure engagement with the upper bearingplate 72 whereupon the caisson shell is bottom anchored to accommodatetension loading thereof. Points or areas of moving contact in theanchoring device are preferably graphite packed, and the ungroutedsection of the socket and the bottom three to four feet of the shell maybe filled with mastic or grease to prevent rusting.

Vlhen the caisson shells of the various foundation units shown inFIGURES 1 and 2 have been engaged on or set in rigid anchorage, i.e. bedrock or a pedestal, in any of the manners above described, and the swaybracings have been installed, the guide collars 48 and locking rings 50may be removed from the caisson shells. The lifting tackle sets 54 arethen attached to the bottoms of the caps 26, and the hoists 56 areoperated to raise the barge 42 on the upper extensions of the caissons.Lifting is simultaneously carried out at the three locations to insureuniform raising of the barge, and also to accommodate such trimming ofthe barge as may be necessary. The barge is raised on the tripod unitsto the re quired height in relation to peak water level, whereupon thebarge comprises a stationary drilling platform, the slots .4 in thebarge being of a length to accommodate such raising of the barge, as isclearly shown in FIG- URE 4.

With the caisson shells set, the sway bracing spides in place, and thebarge elevated, a highly stable, stationary drilling platform isafforded and exploratory drilling may be commenced immediately.

If the exploratory drilling is non-productive and the site is to beabandoned, the drilling equipment is retracted to the barge or platform42, the barge is lowered on the caissons to a floating position on thebody of Water, and the guides and locking rings 59 are again disposedabout the caissons on the towers 4-6. If the caisson shells wereanchored by means of concrete plugs 64, the plugs are drilled out. Ifstub cores were employed, the same are removed, if convenient, afterdrilling out the plugs 64. If the anchoring device shown in FIGURE 4were employed, the top member 84 thereof is threaded out of the sleeve82 and removed. In any event, the caissons are first released from theirbottom anchorage. The spiders 53 are then removed by lifting each spiderby means of the crane 52 to slack off the connections of the ties 62,whereupon the ties may each be detached from one collar and the threecollars and ties raised to the barge. The crane 52 and locking rings 50are thereafter employed to retract the caissons from bed rock tosubstantially the position shown in FIG- URE 3. As the upper pipesection of each caisson is raised above the respective tower 46, it maybe removed from the lower section, thus to restore the apparatussubstantially to its original condition, whereupon the anchors may beweighed and the barge towed to a new drilling location.

As one drilling site is abandoned, the entirety of the apparatusemployed for the temporary island is removed, with the exception of thepedestals and/ or the stub cores, bottom members and sleeves of theanchoring device, if employed, so that there is little if any materialwaste and no remaining obstruction to navigation.

If at the first or subsequent drilling site at producing well is broughtin, or if added stability is desired, the island may be renderedpermanent with particular facility. Specifically, if the caisson shellswere merely driven to refusal in bed rock or a pedestal in the firstinstance, or if the same were temporarily anchored by means solely ofthe concrete plugs 64, the shells are first rigidly anchored at theirbottoms by drilling out the concrete plugs and drilling a socket in bedrock or the pedestal in axial alignment with each caisson shell. Eachsocket is cleared and a charge of grout deposited therein. Reenforcingstub cores 63 or the bottom members 80 of the anchoring devices 70 arethen inserted in the sockets and the grout is permitted to set. If stubcores are employed, as shown in the unit at the left in FIGURE 1, theshell is filled at its lower end with concrete to bond the shell or pipeto the core and thus to bed rock or the pedestal. According to thepresent invention, I prefer to employ the anchoring devices shown inFIGURE 4, which devices are installed in the manner previouslydescribed.

If in the original installation of the caisson shells, the shells werebottom anchored by driving the shells into pedestals prior to settingthereof, or by bonding stub cores in sockets in bed rock or thepedestals and in the lower ends of the shells, or by use of theanchoring device of FIGURE 4, the caissons would already have beenbottom anchored to the extent necessary for a permanent islandinstallation and further bottom anchorage would not be required.

In those instances where contemplated use of the foundation is as atemporary or semi-permanent island or foundation construction, thecaisson shells or pipes are designed to carry the calculated loadwithout necessity for the extra stiffening and bearing value that wouldbe afforded by use of a complete concrete fill and a full length core ina permanent installation. By virture of this design, the caisson shellseven when rigidly anchored at their bottoms are hollow throughoutsubstantially the full length thereof. This affords the distinctadvantages, as will be pointed out hereinafter, of facilitating completeremoval of any possible obstructions, and of accommodating recovery tothe greatest extent possible of reusable components of the foundationwhen the temporary or semi-permanent island or other installation isabandoned. Nevertheless, with this design, the shells afford apermanently usable foundation even in those cases where the contemplatedtemporary nature of the structure proves to be erroneous.

When the caissons of the several foundation units have been rigidlyanchored at their bottoms in any of the manners described, the caps 26of each tripod or conical unit are permanently set. The foundation isthen complete and rigid and the barge 42 comprises a permanent fixedisland from which the operations necessary to oil production or the likemay be carried out. The barge may be locked semi-permanently to theupper end portions of the caissons or the caps 26, whereafter the setsof tackle 54 may be removed. All unnecessary equipment including thetowers 46, guides 48, locks 50, crane 52, tackle sets 54 and hoists 56may then be removed from the barge for use on another rig at a differentlocation.

In all cases, there is little or no waste of equipment. The island,whether temporary, semi-permanent, or permanent, is comprised solely ofits essential components and all additional material may be re-used. Theconversion of the drilling platform to a permanent foundation is readilyeffected at substantial economy, particularly as compared to the priorpractices of the art. Yet, the resultant foundation is completely andoptimumly stable under all loading conditions, and provides an optimum,fixed area for carrying out the functions of oil production or the like.

While the resultant island construction is permanently fixed against theelements to which it may be subjected, the same still affords thedistinct advantage of semi-permanency as concerns its users.Specifically, if the well should run dry, the island may be dismantledby reinstalling thereon the equipment previously described. The barge isfirst released from the caissons and lowered to water level, and therigid cap on each conical unit is removed. The bottom anchorage is theneliminated by release of the anchoring evice or by drilling as may beappropriate according to the anchoring means employed. After eachcaisson has been released from its anchor, the caisson shell may, due tothe fact that it is hollow and of relatively light weight, be raised tothe barge deck, whereby all equipment above bed rock or the pedestals,and thus above the mud line, is removed from the site, so that there isno remaining obstruction to navigation. Moreover, the barge is thenrestored substantially to its oniginally equipped condition for use atother drilling sites.

While the foundation of FIGURES 1 and 2, and the artificial islanddescribed in conjunction therewith, have been shown and described asembodying three of the conical units of my said parent application, itis to be appreciated that any number of the units, each comprised ofthree or more legs, may be employed in any desired pattern to afford arigid foundation adapted to a wide variety of uses. Each of the bottomanchored conical skeletal units affords a point of rigid support, astrong 10 point, which inhibits lateral movement of the barge or otherstructure supported thereby irrespective of the interaction it has withother strong points. Thus, the strong points afford Wide latitude as tonumber and the pattern of placement.

From the foregoing, it is to be appreciated that the present inventionprovides an improved foundation adapted especially for use as atemporary, permanent, or semiperm-anent artificial island, and animproved method of and apparatus for erecting such foundation, that areideally and optimumly suited for use in the manner described inoff-shore oil fields and for other off-shore uses. Thus, all of theobjects and advantages of the invention have been shown to be attainedin an economical, convenient and practical manner.

While I have shown and described what I regard to be the preferredembodiments of my artificial island and of my method of and apparatusfor erecting the same, it will be apreciated that various changes,rearrangements, and modifications may be made therein without departingfrom the scope of the invention, as defined by the appended claims.

i claim:

1. Method of erecting an artificial island in a body of water whichcompnises floating a barge on said body of water whereby it initiallygains vertical support, anchoring said barge to the ground for lateralsupport at the location where said island is to be located, loweringfrom said barge three downwardly divergent tubular casings guidedendwise into engagement with a rigid stratum below the barge, drivingeach easing into tight engagement with the rigid stratum, cutting asocket into the rigid stratum as an axial extension of the bore of saidcasing, disposing a metallic anchoring member partly in the socket andpartly in the bore of the casing, filling each socket with cement tobond the anchoring member to the walls of the socket, connecting saidanchoring member to the inside wall of the casing, connecting the upperends of the convergent casings together at a point above the barge in acommon cap by which the upper ends of the casings are rigidly securedtogether against relative endwise movement with respect to each other toform a stable bottom anchored tripod capable of resisting large forcesapplied to the cap member from any direction, erecting on the bottombelow said barge at least two additional stable tripods as aforesaid toform a polygonal figure, transferring the lateral anchorage of the bargefrom said ground anchorage to said stable tripods, raising the bargefrom the supporting water by transferring the Weight of the barge tosaid stable tripods and holding the same by connection with said capsagainst horizontal and vertical forces whereby said barge forms aplatform supported against overturning by the full strength of the rocksocketed casings in tension and compression longitudinally thereofwithout any substantial bending forces and resisting overturningindependently of vertical loading.

2. Method of erecting an artificial island in a body of water whichcomprises floating a barge on said body of water whereby it gainsvertical support, anchoring said barge to the ground for lateral supportat the location Where said island is to be located, emplacing from saidbarge a series of at least three groups of caissons, said groups beingdisposed in a closed pattern, each group con sisting of three downwardlydivergent upwardly convergent caissons bonded at their lower ends intosockets in underlying firm earth strata for supporting tension orcompression axially of the caissons, and bonding their upper endstogether rigidly against longitudinal or lateral movement with respectto each other by a cap, transferring the lateral support of said bargeto said groups of caissons and transferring the weight of said barge tothe caps of said groups and raising the barge above the level of theWater, whereby said barge constitutes a platform supported by saidgroups of caissons against overturning independently of verticalloading, and capable of resisting lateral 11 and vertical loads withoutimposing bending stresses upon the caissons.

3. The method of claim 2 applied at a location where the bottom of thebody of water comprises rock with overburden ineffective to supportdriven piles, and wherein the lower ends of the caissons are projectedinto and bonded into sockets in the rock for supporting tension or CO1pression along the longitudinal axes of the caissons to substantiallytheir full strength and without substantial bending stress beingproduced in said caissons by horizontal forces acting upon saidplatform.

4. Method of erecting an artificial island in a body of water whichcomprises floating a barge upon said body of Water, anchoring said bargeto the ground for lateral support at the location where said island isto be erected, emplacing from said barge a series of at least threebottom anchored top bonded tripods by projecting down from the barge andanchoring into rigid strata downwardly divergent caissons in sets ofthree to form tripods, said three caissons of each set converging attheir upper ends, bonding said convergent caissons of each set of threetogether at their upper ends against relative movement longitudinallyand laterally, whereby forces from any direction applied to said bondedends are resisted Without incurring bending stresses in said caissons,transferring the lateral support of the barge to said bonded togetherupper ends of said tripods, transferring the weight of said barge tosaid bonded together upper ends of said tripods and raising the bargeabove the level of the water whereby said barge constitutes a platformcapable of resisting lateral and vertical loads without imposing bendingstresses upon the caissons.

5. A structure of the class described for providing an artificial islandin a body of water comprising a buoyant barge having releasable meansfor anchoring the same on the water at the intended location of theisland, a series of at least three tripods arranged at the corners of apolygon consisting of three downwardly divergent caissons bonded inrigid sockets in firm strata at their lower ends whereby they arecapable of rigidly sustaining loads in tension and compression in.thedirection of their longitudinal axes, said caissons converging at theirupper ends, caps in which said upper convergent ends are bonded togetheragainst movement relative to each other for each tripod, said bargehaving means employed while the barge is floating in the water to guidethe caissons and emplace them, and means on said barge for connecting itwith the caps of said tripods to carry the weight of the barge upon saidcaissons when the barge is raised out of the water, said barge whenraised out of the water and sup ported upon said caps being capable ofresisting horizontal forces from any compass direction by tension andcompression in said caissons in the direction of their longitudinal axeswithout substantial bending stresses and being stable againstoverturning independently of vertical loading.

References Cited in the file of this patent UNITED STATES PATENTS1,164,085 Goldsborough Dec. 14, 1915 1,365,197 Scott Jan. 11, 19211,449,236 Malone Mar. 20, 1923 2,472,869 Travers June 14, 1949 2,475,933Woolslayer July 12, 1949 2,531,983 McCoy Nov. 28, 1950 2,589,146Samuelson Mar. 11, 1952 2,600,761 Halliburton June 17, 1952 2,608,830Burrell Sept. 2, 1952 2,653,451 McCullough Sept. 29, 1953 2,699,042Hayward Jan. 11, 1955 2,740,261 Stark Apr. 3, 1956 2,774,218 Hazak Dec.18, 1956 2,775,095 Harris Dec. 25, 1956 2,927,435 Upson Mar. 8, 1960

1. METHOD OF ERECTING AN ARTIFICIAL ISLAND IN A BODY OF WATER WHICHCOMPRISES FLOATING A BARGE ON SAID BODY OF WATER WHEREBY IT INITIALLYGAINS VERTICAL SUPPORT, ANCHORING SAID BARGE TO THE GROUND FOR LATERALSUPPORT AT THE LOCATION WHERE SAID ISLAND IS TO BE LOCATED, LOWERINGFROM SAID BARGE THREE DOWNWARDLY DIVERGENT TUBULAR CASINGS GUIDEDENDWISE INTO ENGAGEMENT WITH A RIGID STRATUM BELOW THE BARGE, DRIVINGEACH CASING INTO TIGHT ENGAGEMENT WITH THE RIGID STRATUM, CUTTING ASOCKET INTO THE RIGID STRATUM AS AN AXIAL EXTENSION OF THE BORE OF SAIDCASING, DISPOSING A METALLIC ANCHORING MEMBER PARTLY IN THE SOCKET ANDPARTLY IN THE BORE OF THE CASING, FILLING EACH SOCKET WITH CEMENT TOBOND THE ANCHORING MEMBER TO THE WALLS OF THE SOCKET, CONNECTING SAIDANCHORING MEMBER TO THE INSIDE WALL OF THE CASING, CONNECTING THE UPPERENDS OF THE CONVERGENT CASINGS TOGETHER AT A POINT ABOVE THE BARGE IN ACOMMON CAP BY WHICH THE UPPER ENDS OF THE CASINGS ARE RIGIDLY SECUREDTOGETHER AGAINST RELATIVE ENDWISE MOVEMENT WITH RESPECT TO EACH OTHER TOFORM A STABLE BOTTOM ANCHORED TRIPOD CAPABLE OF RESISTING LARGE FORCESAPPLIED TO THE CAP MEMBER FROM ANY DIRECTION, ERECTING ON THE BOTTOMBELOW SAID BARGE AT LEAST TWO ADDITIONAL STABLE TRIPODS AS AFORESAID TOFORM A POLYGONAL FIGURE, TRANSFERRING THE LATERAL ANCHORAGE OF THE BARGEFROM SAID GROUND ANCHORAGE TO SAID STABLE TRIPODS, RAISING THE BARGEFROM THE SUPPORTING WATER BY TRANSFERRING THE WEIGHT OF THE BARGE TOSAID STABLE TRIPODS AND HOLDING THE SAME BY CONNECTION WITH SAID CAPSAGAINST HORIZONTAL AND VERTICAL FORCES WHEREBY SAID BARGE FORMS APLATFORM SUPPORTED AGAINST OVERTURNING BY THE FULL STRENGTH OF THE ROCKSOCKETED CASINGS IN TENSION AND COMPRESSION LONGITUDINALLY THEREOFWITHOUT ANY SUBSTANTIAL BENDING FORCES AND RESISTING OVERTURNINGINDEPENDENTLY OF VERTICAL LOADING.